Machine Safety and Process Safety
August 26, 2021
When it comes to establishing machine safety and lowering risk in an industrial workplace, many people are often confused by Safety Integrity Levels (SIL) and Performance Levels (PL). This confusion is expected as the two terms and their associated standards work toward the same result: eliminating or minimizing hazards and risks within industrial workplaces.
Both SIL and PL apply to many industrial applications. Still, it is important to understand the differences between SIL and PL before deciding which safety standard to follow as they relate to different specifications.
SILs come at three levels: 1, 2, or 3. The levels are determined through the following factors:
PLs occur in five performance levels: a, b, c, d, and e. These levels of process safety are determined through three factors:
When it comes to establishing machine safety and lowering risk in an industrial workplace, many people are often confused by Safety Integrity Levels (SIL) and Performance Levels (PL). This confusion is expected as the two terms and their associated standards work toward the same result: eliminating or minimizing hazards and risks within industrial workplaces.
Both SIL and PL measure the reduction in risk provided by a safety function of a control system. However, they do deviate from one another in significant ways.
SIL for Machine Safety Versus PL and Process Safety
Both PL and SIL, when applied to industrial machinery, are measurements of the probability of failure within your machine safety or process safety system. They consider user error, safeguards, designs and possible design faults, safety detectors within a device, and many other factors while calculating the failure probability. SIL and PL answer the same vital questions surrounding industrial machine safety and process safety standards: How safe are our machines? And for how long will they remain safe?Both SIL and PL apply to many industrial applications. Still, it is important to understand the differences between SIL and PL before deciding which safety standard to follow as they relate to different specifications.
Machine Safety Standards & SILs
Machine safety uses the EN 62061 safety standard requirements for electrical and electronic control systems. EN 62061 is suitable for more complex systems. When you are operating within EN 62061, all risk assessments will be measured in terms of SIL.SILs come at three levels: 1, 2, or 3. The levels are determined through the following factors:
- Severity of harm
- Frequency and exposure time to a hazard
- Possibility of a hazard happening
- Possibility of avoiding or limiting harm
Process Safety Standards & PLs
Process safety uses the EN 13849 safety standard requirements. EN 13849 is applicable for simpler safety-related control systems. These systems are generally comprised of off-the-shelf safety components, pneumatic components, or hydraulic components. When your application follows EN 13849, your risk assessments will be determined at a PL.PLs occur in five performance levels: a, b, c, d, and e. These levels of process safety are determined through three factors:
- Severity of injury
- Frequency and exposure time to the hazard
- Possibility of avoiding the hazard or limiting harm.
How Can I Create a Safer Work Environment in My Industry?
While there isn’t a strict guideline to help you use machine safety or process safety standards, your choices for safety systems may be influenced by:- Prior experience with a particular methodology
- Safety controls that are not based on electrical or electronic systems
- Customer requirements
- Working within an industry where existing machinery uses SIL
- Risk assessment results